Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Process of treating scrap or waste product containing solid...
Reexamination Certificate
2001-04-24
2003-12-09
Cooney, Jr., John M. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Process of treating scrap or waste product containing solid...
C521S049500, C521S170000
Reexamination Certificate
active
06660779
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a technology for recycling rigid polyurethane foam. More specifically, the present invention relates to a technology to decompose rigid polyurethane foam to recycle it as a material of an insulator of a refrigerator or the like.
2. Description of the Related Art
From a viewpoint of resource conservation, recycling of scrapped household electric appliances such as refrigerators and televisions has been emphasized, and various endeavors have been undertaken for that purpose. In recycling of refrigerators, metallic materials such as iron plates and copper pipes can be recycled with relative ease. However, plastics, especially rigid polyurethane foam as a thermosetting resin, which is commonly used for insulators, is difficult to melt and recycle. Generally, such plastics are disposed of in reclaimed lands or incinerated, or they are reused as fillers.
Under this condition, techniques to decompose polymer materials by treating with supercritical water and sub-critical water have been proposed. For example, JP-A-10-310663 suggests a method for decomposing and recycling polyurethane resin. The reference describes decomposition of polyurethane resin by using supercritical or sub-critical water in order to recover starting compounds of the polyurethane resin or available starting derivatives. Japanese Patent No. 2885673 describes decomposing polymer materials by using supercritical or sub-critical water in order to decompose the materials into oils.
However, since rigid polyurethane foam included in a scrapped refrigerator is covered with an iron plate or with an ABS resin, it cannot be decomposed by treating with supercritical water. Various polymer materials used for interior members of a refrigerator, such as polypropylene resin, can be decomposed by using supercritical water or sub-critical water. However, when the members are decomposed together, various resulting low molecular weight materials will be melted as impurities in the mixed materials. As a result, the material cannot be reused for a rigid polyurethane foam material.
Therefore, for the purpose of industrial recycling, discrimination of rigid polyurethane foam from scrapped refrigerators is the most important to recycle starting compounds of polyurethane resin or any available starting derivatives. The rigid polyurethane foam is requested to be free of dissimilar materials or impurities. Another fundamental aim is to establish waste treatment for decomposing and recycling iron and non-ferrous metals and providing a high recycling rate as an entire system.
The chemical structure of rigid polyurethane foam to be decomposed affects the determination on starting compounds of polyurethane resin obtainable by decomposition and available starting derivatives. The factors vary depending on the materials of the original rigid polyurethane foam. Therefore, it is important to select a method of manufacturing materials suitable for the original rigid polyurethane foam.
Still another aim for recycling is to use polyurethane resin compounds obtainable by decomposition and available derivatives, and reuse the materials for insulators of refrigerators.
A critical problem is that when rigid polyurethane foam used in a scrapped refrigerator is not identified properly, suitable methods for treating and manufacturing cannot be determined, and this prevents recycling.
SUMMARY OF THE INVENTION
In order to solve the problem described above, the present invention provides a method of manufacturing a raw material of rigid polyurethane foam, a method of manufacturing a refrigerator from recycled rigid polyurethane foam, and a refrigerator, so that the recycling rate for scrapped refrigerators is improved, and thus, the present invention serves for resource conservation.
The method includes steps of shredding a scrapped refrigerator containing rigid polyurethane foam in order to obtain rigid polyurethane foam lumps, grinding the lumps in order to obtain a rigid polyurethane foam powder, liquefying the rigid polyurethane foam powder by either an aminolysis or glycolysis reaction, and reacting the thus obtained liquefied rigid polyurethane foam powder with a supercritical water or sub-critical water in order to decompose the rigid polyurethane foam.
Accordingly, rigid polyurethane foam free of impurities such as resins can be extracted on an industrial scale from a rigid polyurethane foam lump contained in a scrapped refrigerator. It should be specifically noted that since the rigid polyurethane foam is liquefied, fragments of impurities such as other polypropylene resins can be filtered to obtain a pure composition of hard polyurethane foam. By treating the liquefied rigid polyurethane foam powder with supercritical or sub-critical water, the composition can be decomposed into amines and polyol of rigid polyurethane foam having substantially no impurities.
Preferably in the above method, the rigid polyurethane foam powder is liquefied by mixing with an additive comprising at least one compound selected from ethylene glycol, propylene glycol, monoethanolamine and tolylenediamine before heating. Since the compound serves to decompose and liquefy a part of the urethane bonding selectively, fragments of impurities can be removed efficiently.
Preferably in the above method, a ratio of the additive to the rigid polyurethane foam powder is from 0.4:1 to 5.0:1 by weight, and the reaction temperature ranges from 100 to 250° C.
Preferably in the above method, a ratio of the supercritical/sub-critical water to the liquefied rigid polyurethane foam powder is from 0.4:1 to 5.0:1 by weight, and the liquefied rigid polyurethane foam powder is reacted with the supercritical/sub-critical water at a temperature ranging from 190 to 400° C. and at a pressure ranging from 10 to 25 MPa.
Preferably in the above method, an average particle diameter of the rigid polyurethane foam powder ranges 1 &mgr;m to 3 mm.
Preferably in the method, the rigid polyurethane foam is manufactured by foaming either a diphenylmethane diisocyanate composition or a tolylene diisocyanate composition.
A method of manufacturing rigid polyurethane foam according to the present invention comprises steps of:
shredding a scrapped refrigerator including rigid polyurethane foam in order to separate lumps of rigid polyurethane foam,
grinding the rigid polyurethane foam lumps into a rigid polyurethane foam powder,
liquefying the rigid polyurethane foam powder by an aminolysis reaction or a glycolysis reaction,
reacting the liquefied rigid polyurethane foam powder with either supercritical water or sub-critical water in order to decompose the rigid polyurethane foam powder to obtain a crude material,
fractionating the crude material, and subsequently addition-polymerizing the fractionated ingredient with at least one of ethylene oxide and propylene oxide in order to synthesize polyetherpolyol.
A method of manufacturing rigid polyurethane foam according to the present invention comprises steps of:
shredding a scrapped refrigerator including rigid polyurethane foam in order to separate lumps of rigid polyurethane foam,
grinding the rigid polyurethane foam lumps into a rigid polyurethane foam powder,
liquefying the rigid polyurethane foam powder by an aminolysis reaction or a glycolysis reaction,
reacting the liquefied rigid polyurethane foam powder with either supercritical water or sub-critical water in order to decompose the rigid polyurethane foam powder to obtain a crude material, and
fractionating the crude material and subsequently synthesizing isocyanate by using the fractionated ingredient as a starting material.
It is preferable in the present invention that the crude material is obtained by decomposing rigid polyurethane foam made from a tolylene diisocyanate composition.
Accordingly, the tolylene diisocyanate-based rigid polyurethane foam used for a refrigerator insulator can be recycled easily on an industrial scale. Particularly, tolylenediamine-based polyetherpolyol can be synthesized from tolylenediamine
Uekado Kazutaka
Yuasa Akiko
Cooney Jr. John M.
Matsushita Refrigeration Company
Merchant & Gould P.C.
Mueller Douglas P.
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